This is invention relates to a roll core releasing device which automatically and reliably releases an empty core of a rolled object from holding members of a rolled object holding apparatus such as a paper roll holding apparatus for a rotary press after the rolled object such as a paper roll on the core which is held at its ends on the holding members has been fed and then run out.
One example of the conventional device for releasing the empty core from the holding members, as used on a paper roll holding device for a rotary press, may be found in the Japanese Patent Publication No. 38496/1981 (line 42 of column 8 to line 4 of column 9). In this common example the holding members inserted into the hollow core from each side are retracted out of the hollow core to allow the core to fall by gravity, thus releasing the core from the holding members. In this case, only one of the holding members that hold the core from both sides is advanced into and retracted from the hollow core. When the distance between the opposed holding members exceeds the length of the core, the core falls by gravity (reference: "SHIMBUN INSATSU" (Newspaper Printing): vol. on Printing, revised edition, published by Nihon Shimbun Kyokai on Oct. 31, 1980 (p. 66 1.13 of right column to p. 67 1.6 of left column).
In recent years, growing efforts are being made to increase the printing speed of the rotary press and the diameter and volume of the paper roll. Because of these tendencies, inertia of the paper roll during the operation of the rotary press becomes larger and, to synchronize the rotation of the paper roll with the printing speed of the rotary press, it is necessary for holding members to give a secure and reliable restraining holding to paper roll.
For that purpose, the paper roll holding apparatus or rolled object holding apparatus employs a mechanism to increase the force of engagement of the holding members with the inner circumferential surface of the hollow core. The increased grip, however, has resulted in still retained engagement force between one of the holding members (generally the one which does not retract) and the inner circumferential surface of the hollow core often when the holding member has retracted and the distance between the opposed holding members has exceeded the length of the core, thus requiring manual work on the part of an operator to completely release the old core during the process of automatic replacement of the rolled object.